Arterial filter with aspiration and methods of use

ABSTRACT

A filter comprising a porous material is arranged in a generally conical shape having an expandable base and a vertex. An elongate member having a proximal end and a distal end is attached to the expandable base of the porous material at a first circumferential location of the expandable base and extends perpendicularly from a central axis of the filter. An aspiration tube, for removing embolic material under vacuum, communicates with an area at the first circumferential location of the expandable base. Methods of using the filter and occluding devices for protecting a patient from embolization during cardiovascular procedures are described.

[0001] This is a continuation of U.S. application Ser. No. 09/473,584,filed Dec. 28, 1999, now U.S. Pat. No. 6,406,471, the contents of whichare incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to medical devices forprotecting a patient from embolization during cardiovascular procedures.More particularly, the devices comprise a filter for temporary placementin a patient's vessel, and an aspiration tube communicating with aportion of the filter, e.g., a reservoir tip at a vertex of the filter,for aspirating embolic material, including air and gas.

BACKGROUND OF THE INVENTION

[0003] Aspiration catheters are frequently used during surgical orinterventional procedures for removing thromboembolic material, e.g.,air, fluid, thrombi, calcium, atheromatous plaque, and/or tissue debris,from a patient's body cavity. During cardiovascular procedures, such ascoronary artery bypass grafting surgery, ventricular septal defectrepair, heart valve repair or replacement, ventricular myomectomy,aortic aneurysm repair, or aortic thrombectomy, removal ofthromboembolic material from a cardiac chamber and/or the aorta isimportant since distal embolization may result in ischemia or infarctionof peripheral organs, particularly the brain.

[0004] Endovascular techniques have been used widely as an effective andreliable alternative to surgical intervention in selected patients fortreatment of vascular stenosis. It is well recognized that one of thecomplications associated with endovascular techniques is the dislodgmentof embolic materials generated during manipulation of the vessel,thereby causing occlusion of the narrower vessels downstream andischemia or infarct of the organ which the vessel supplies.

[0005] Several arterial and venous filters have been designed forentrapment of embolic debris generated during surgical or endovascularprocedures. An aspiration catheter is often required for completeremoval of embolic debris. Current aspiration catheters are designed toremove fluid and tissue debris in a body cavity. Removal of air,however, is difficult because the air bubbles tend to accumulate againstthe vessel wall at a position difficult to reach. Thus, removal ofembolic material is often not complete and patients remain at risk forair embolization.

[0006] Thus, there is a need for devices and methods which are capableof capturing and effectively removing embolic material within apatient's body tissue or cavity during surgical or endovascularprocedures.

SUMMARY OF THE INVENTION

[0007] The present invention provides an intravascular filter fortemporary placement in a patient's vessel, such as an artery or vein. Ina first embodiment, the filter comprises a porous material arranged in agenerally conical shape having a base and a vertex. The base isexpandable and collapsible. A reservoir tip is located at the vertex ofthe cone for collecting filtered embolic material. The tip alsocommunicates with a distal end of an aspiration catheter. In certainembodiments, the reservoir tip comprises a nonporous material, e.g.,latex. In other embodiments, the distal end of the aspiration tubeextends only to the outer edge of the filter, e.g., the point ofinsertion into the vessel.

[0008] In another embodiment, the filter is mounted on a cannula, andthe aspiration tube extends proximally within the cannula. The proximalend of the aspiration tube communicates with a vacuum pump.

[0009] In another embodiment, the filter is mounted on an insertionhandle, and the aspiration tube extends proximally within the insertionhandle. The aspiration tube includes an infusion port at the distal endfor infusion of fluid, such as saline or heparin.

[0010] In another embodiment, the filter is mounted on a distal end ofan obturator, and the aspiration tube extends proximally within theobturator. The distal end of the aspiration tube may further include aturbine which extends into the reservoir tip for removing large embolicparticles.

[0011] The present invention further provides occluding devices fortemporary placement in a patient's vessel, such as an artery or vein. Ina first embodiment, the device comprises a nonporous material arrangedin a conical shape having an expandable base and a vertex. A reservoirtip is located at the vertex of the cone for collecting filtered embolicmaterial. The tip also communicates with a distal end of an aspirationcatheter. In certain embodiments, the device is mounted on an insertionhandle, having the aspiration tube extending proximally within thehandle. Alternatively, the device is mounted on a cannula or anobturator.

[0012] The invention also provides methods for protecting a patient fromembolization using the filter or occluding devices described above.During cardiopulmonary bypass, for example, the filter or the occludingdevice is placed in a collapsed state and inserted into the patient'saorta. The filter or the occluding device is expanded to capture embolicmaterial, including air, fluid, thrombi, calcium, atheromatous plaque,and/or tissue debris. The proximal end of the aspiration catheter isconnected to a vacuum, and emboli are aspirated under negative pressureand removed from the aorta. The filter or the occluding device is thencollapsed and removed from the aorta.

[0013] It will be understood that there are several advantagesassociated in using the devices and methods disclosed herein forpreventing embolic complication during cardiovascular procedures. Forexample, (1) the filter is adapted for temporary placement in apatient's artery or vein; (2) the filter communicates with an aspirationtube for removal of embolic material; (3) the filter includescapability, such as a turbine or infusion port, for breakup of largeembolic particles; (4) the occluding device provides aortic occlusionduring cardiopulmonary bypass in addition to providing protection fromdistal embolization; (5) using the occluding device in place of anaortic clamp minimizes vascular injury caused by the clamp; and (6) thedevices remove air and gas in addition to particles liable to causedistal embolization.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1A depicts a filter with aspiration capabilities deployed ina vessel.

[0015]FIG. 1B depicts a lateral view of a filter having a reservoir tipcommunicating with an aspiration catheter.

[0016]FIG. 1C depicts a distal view of the filter of FIG. 1B.

[0017]FIG. 2A depicts a lateral view of another embodiment of the filterincluding a conical-shaped nonporous material.

[0018]FIG. 2B depicts a distal view of the filter of FIG. 2A.

[0019]FIG. 3A depicts another embodiment of the filter having aninfusion port.

[0020]FIG. 3B depicts another embodiment of the filter having anangulated infusion port.

[0021]FIG. 4 depicts another embodiment of the filter having a turbineat a distal end of the aspiration catheter.

[0022]FIG. 5 depicts the filter of FIG. 1A passing through anintroducer.

[0023]FIG. 6 depicts an occluder deployed in a vessel.

[0024]FIG. 7 depicts the filter of FIG. 1A mounted on a distal end of aninsertion handle.

[0025]FIG. 8 depicts the filter of FIG. 1A deployed through anobturator.

[0026]FIG. 9 depicts the filter of FIG. 1A mounted on a distal end of acannula.

[0027]FIG. 10 depicts a dam deployed in the aorta during cardiopulmonarybypass.

DETAILED DESCRIPTION

[0028] The devices and methods disclosed herein are adapted fortemporary placement in a patient's artery or vein for entrapment andremoval of embolic debris. The devices are particularly useful incardiovascular surgeries for preventing distal embolization toperipheral organs. An embodiment of the filter is depicted in FIGS. 1A,1B, and 1C. Filter 10 comprises a porous material arranged in a conicalshape having expandable base 11 and vertex 12. Reservoir tip 15 islocated at vertex 12 for collecting embolic material, and communicateswith distal port 26 at distal end 22 and lumen 25 of aspiration tube 20.A proximal end (not shown) of the aspiration tube is adapted forattachment to a vacuum. In this embodiment, reservoir tip 15 comprises anonporous material, e.g., latex. In other embodiments, the reservoir tipis constructed of the same material as the filter mesh.

[0029] The construction and use of expansion means and associated filtermesh have been thoroughly discussed in earlier applications includingBarbut et al., U.S. application Ser. No. 08/533,137, filed Nov. 7, 1995,Barbut et al., U.S. application Ser. No. 08/580,223, filed Dec. 28,1995, Barbut et al., U.S. application Ser. No. 08/584,759, filed Jan. 9,1996, Barbut et al., U.S. Pat. No. 5,769,816, filed Apr. 30, 1996,Barbut et al., U.S. application Ser. No. 08/645,762, filed May 14, 1996,and Barbut et al., U.S. Pat. No. 5,662,671, and the contents of each ofthese prior applications are expressly incorporated herein by referencein their entirety.

[0030] Once appropriate physical characteristics are determined,suitable mesh can be found among standard meshes known in the art. Forexample, polyester meshes may be used, such as meshes made by SaatiCorporations and Tetko Inc. These are available in sheet form and can beeasily cut and formed into a desired shape. In a preferred embodiment,the mesh is sonic welded into a cone shape. Other meshes known in theart, which have the desired physical characteristics, are also suitable.For example, the filter may be constructed of a thin film material withlaser cut holes. Anticoagulant, such as heparin and heparinoids, may beapplied to the mesh to reduce the chances of blood clotting on the mesh.Anticoagulants other than heparinoids also may be used, e.g., ReoPro(Centocor). The anticoagulant may be painted or sprayed onto the mesh. Achemical dip comprising the anticoagulant also may be used. Othermethods known in the art for applying chemicals to mesh may be used.

[0031] Another embodiment of the filter is depicted in FIGS. 2A and 2B.Reservoir tip 15 comprises a nonporous material, e.g., latex, whichextends into a portion of filter 10 and covers area 30. Area 30 isshaped like a sector of a circle having two radii and the included arc.In certain embodiments, latex may extend to cover distal end 22 ofaspiration tube 20 as shown in FIG. 2B.

[0032]FIG. 3A depicts another embodiment of aspiration tube 20 havinginfusion port 40 at distal end 22. Infusion port 40 communicates withinfusion lumen 41, which is included in the aspiration catheter. Theinfusion port and lumen are adapted for infusion of fluid, e.g., saline,or Ringer's lactate, for irrigating embolic material, and pharmaceuticalagent, e.g., heparin or streptokinase to facilitate breakup of largethrombi dislodged within tip 15. Infusion port 40 may be angled relativeto the axis of infusion lumen 41 as depicted in FIG. 3B.

[0033] In another embodiment, distal end 22 of aspiration tube 20includes turbine 44 as shown in FIG. 4. The turbine can be activatedproximally to disintegrate or break up large embolic material tofacilitate removal into lumen 25.

[0034] In using the filter and aspiration device of FIGS. 1A-1C, thefilter can be introduced intravascularly directly through an openincision on the vessel. More preferably, the filter is placed in acollapsed state and inserted through lumen 55 of introducer 50 asdepicted in FIG. 5. Introducer 50 is first introduced through anincision on vessel 100. Suture(s) may be placed on flange 51 tostabilize the introducer onto vessel 100. Filter 10 is then insertedinto lumen 55 and deployed in the vessel. Aspiration tube 20 extendsproximally within introducer 50 and is connected to a vacuum at itsproximal end. The filter is expanded at its base which covers theperimeter of the vessel wall. The filter captures and the reservoir tipcollects embolic material, e.g., air, fluid, thrombi, calcium,atheromatous plaque, and/or tissue debris, generated during theprocedure. Emboli are aspirated into lumen 35 of aspiration tube 20 fromthe reservoir tip under negative pressure and removed. Emboli are alsoremoved after the filter is collapsed and retrieved from introducer 50.In this way, removal of embolic material liable to cause distalembolization during cardiovascular procedures is maximized.

[0035]FIG. 6 depicts vessel occluding device 60 deployed in aorta 101.The occluder comprises a non-permeable or semi-permeable materialarranged in a generally conical shape having expandable base 11 andvertex 12. Reservoir tip 15 is located at vertex 12 for collectingembolic material. Distal port 26 and lumen 25 of aspiration tube 20communicates with tip 15. The device is most useful in cardiovascularsurgeries requiring cardiopulmonary bypass during isolation of coronaryarteries from the peripheral vascular circulation. Using occludingdevice 60 in place of an aortic clamp, injury to the aortic wall, suchas dissection and hematoma, can be minimized.

[0036] In use, during cardiopulmonary bypass, for example, occluder 60is placed in a collapsed state and introduced into aorta 101 upstream ofthe placement of aortic cannula 110. Occluder 60 is then expanded toocclude the aortic lumen. Oxygenated blood is infused, generally atapproximately 3 to 4 liters/minute, through aortic cannula 110downstream in aorta 101 to perfuse peripheral organs. Embolic materialgenerated during cardiovascular surgery is collected in reservoir tip 15of occluder 60. Since the heart is arrested during the procedure,pressure in the aorta distal to occluder 60 is higher than the pressureproximal to the occluder. As a result, blood flows from the highpressure side to the low pressure side, and in absence of aspiration,this reverse flow prevents the particles of emboli from reaching thefilter, instead causing embolic particles to build up in the coronaryarteries. With aspiration, however, blood and the embolic material areremoved under vacuum through aspiration tube 20.

[0037] Occluder 60 is activated to provide aspiration at cross-clampremoval such that a slightly lower pressure would exist in the ascendingaorta proximal to occluder 60 and distal to the region from where thecross-clamp was removed. Blood flows from the high pressure downstreamportion of the aorta that is perfused by arterial return cannula 110 toupstream of occluder 60 because (1) small gaps are present between thevessel wall and the isolating filter/dam 60, and/or (2) the isolatingfilter/dam 60 is semipermeable. The permeable portion is designed toenhance flow into the ascending aorta proximal occluder 60, causingparticles to be swept into the aspiration zone for removal. In anothermethod, occluder 60 is non-permeable and cuffed with a balloon, therebyremoving the need for a cross-clamp.

[0038] In another method, the proximal end of the aspiration tube isattached to a vacuum and an extracorporeal filter. In this way, blood orfluid is removed from the proximal aorta at a rate of 0.5 to 1liter/min, is filtered free of debris, and is returned to the distalaorta through aortic cannula 110 at a rate of 3 to 4 liters/min, therebyminimizing blood loss.

[0039] Filter 10 can be mounted on a distal end of insertion handle 65and inserted into access lumen 66 of cannula 110 as depicted in FIG. 7.In use, cannula 110 and access port 67 are inserted through an incisionon aorta 101. Suture(s) may be placed on flange 68 to secure the cannulaonto aorta 101. Filter 10 in a collapsed state is inserted throughaccess lumen 66 and deployed in the aorta. Aspiration tube 20 extendsproximally within insertion handle 65 and is connected through proximalend 69 of the handle to pressure monitor 70, which is then connected tovacuum 71. The aspirated blood and fluid with the embolic debris fromreservoir tip 15 can be passed through an extracorporeal filter andreturned to a venous return cannula or arterial cannula 110.

[0040] The filter can also be deployed using obturator 75 as depicted inFIG. 8. Filter 10 is mounted on a distal end of obturator 75. Theobturator carrying the filter in a collapsed state is inserted intoaccess lumen 66 to deploy filter 10 in aorta 101. Aspiration tube 20extends proximally within obturator 75 and is connected through proximalend 76 of the obturator to pressure monitor 70 and vacuum 71. Aftercompletion of cardiovascular procedures, vacuum is disconnectedproximally, and obturator 75 is withdrawn, removing filter 10 andaspiration tube 20.

[0041]FIG. 9 depicts filter 10 mounted on distal end 79 of cannula 110.Aspiration tube 20 extends proximally within the cannula housing and isconnected to pressure monitor 70 and vacuum 71. Alternatively, theaspiration tube may terminate just inside the vessel as shown also inFIG. 9. This embodiment applies as well to an aspiration tube carried byan obturator or the handle of a filter. In this manner, air emboli,which tend to rise within the vessel, will migrate close to theaspiration port and be removed.

[0042] By way of example, when the filter disclosed herein is intendedfor use in the aorta, the area of the mesh required for the device iscalculated from Bernoulli's equation as described in our earlierapplications including Barbut et al., U.S. application Ser. No. ______,U.S. application Ser. No. 08/553,137, filed Nov. 7, 1995, Barbut et al.,U.S. application Ser. No. 08/580,223, filed Dec. 28, 1995, Barbut etal., U.S. application Ser. No. 08/584,759, filed Jan. 9, 1996, Barbut etal., U.S. Pat. No. 5,769,816, filed Apr. 30, 1996, and Barbut et al.,and U.S. application Ser. No. 08/645,762, filed May 14, 1996, all ofwhich are incorporated herein by reference in their entirety.

[0043] In the embodiment of the filter that is to be used in the aorta,mesh with dimensions within the following ranges is desirable: mesh areais 0.5-10 in², more preferably 1-9 in², more preferably 2-8 in², morepreferably 3-8 in², more preferably 4-8 in², more preferably 5-7 in²;mesh thickness is 60-280 μm, more preferably 70-270 μm, more preferably80-260 μm, more preferably 90-250 μm, more preferably 100-250 μm, morepreferably 120-230 μm, more preferably 140-210 μm; thread diameter is30-145 μm, more preferably 40-135 μm, more preferably 50-125 μm, morepreferably 60-115 μm, more preferably 70-105 μm, and pore size is 500 μmor less, more preferably 400 μm or less, more preferably 300 μm or less,more preferably 200 μm or less, more preferably 100 μm or less, morepreferably 50 μm or less and usually larger than at least a red bloodcell. In a preferred embodiment of the invention, mesh area is 2-8 in²,mesh thickness is 60-200 μm, thread diameter is 30-100 μm, and pore sizeis 50-300 μm. In a further preferred embodiment of the invention, mesharea is 3-5 in², mesh thickness is 60-150 μm, thread diameter is 50-80μm, and pore size is 100-250 μm.

[0044] During cardiovascular surgeries, it is known that distalembolization from embolic debris generated from the proximal aortaoccurs during removal of aortic cross-clamping. Occluder or dam 60mounted on a distal end of insertion handle 65 can be utilized tominimize embolic complications as depicted in FIG. 10. In use, dam 60 isinserted into access lumen 66 and deployed in aorta 101 shortly beforediscontinuation of cardiopulmonary bypass. When aortic cross clamp 120is removed, aspiration through tube 20 is initiated and continued forapproximately 30 seconds. In this way, blood and embolic material in theproximal aorta flow downstream into dam 60 and are aspirated andremoved, thereby preventing embolization to peripheral organs. Afteraspiration, dam 60 is collapsed and removed from aorta 101 tore-establish blood flow.

[0045] The length of the aspiration catheter will generally be between10 and 100 centimeters for aortic use, preferably approximately between20 and 50 centimeters. The inner diameter of the catheter will generallybetween 0.2 and 2 millimeters, preferably approximately between 0.5 and1 millimeter. The filter will be capable of expanding to an outerdiameter of at least 0.2 centimeters, more preferably at least 0.5centimeters, more preferably at least 1.0 centimeters, more preferablyat least 1.5 centimeters, more preferably at least 2.0 centimeters, morepreferably at least 2.5 centimeters, more preferably at least 3.0centimeters, more preferably at least 3.5 centimeters, more preferablyat least 4.0 centimeters, more preferably at least 4.5 centimeters, morepreferably at least 5.0 centimeters. The filter will be capable ofcontracting to an outer diameter of between 0.05 and 2.0 millimeters,preferably approximately between 0.8 and 1.2 millimeters. These rangescover suitable diameters for both pediatric and adult use. The foregoingranges are set forth solely for the purpose of illustrating typicaldevice dimensions. The actual dimensions of a device constructedaccording to the principles of the present invention may obviously varyoutside of the listed ranges without departing from those basicprinciples.

[0046] Although the foregoing invention has, for the purposes of clarityand understanding, been described in some detail by way of illustrationand example, it will be obvious that certain changes and modificationsmay be practiced which will still fall within the scope of the appendedclaims. Moreover, it will be understood that each and every featuredescribed for any given embodiment or in any reference incorporatedherein, can be combined with any of the other embodiments describedherein.

What is claimed is:
 1. A filter, comprising: a porous material arrangedin a generally conical shape having an expandable base and a vertex; anelongate member having a proximal end and a distal end attached to theexpandable base of the porous material at a first circumferentiallocation of the expandable base and extending perpendicularly from acentral axis of the filter; and an aspiration tube having a proximalend, a distal end, and a lumen therebetween, the lumen communicatingwith a port at the distal end, the distal end of the aspiration tubecommunicating with an area at the first circumferential location of theexpandable base.
 2. The filter of claim 1, further comprising areservoir tip located at the vertex of the cone for collecting filteredembolic material.
 3. The filter of claim 2, wherein the reservoir tipcomprises a nonporous material.
 4. The filter of claim 1, furthercomprising a vacuum pump communicating with the proximal end of theaspiration tube.
 5. The filter of claim 1, further comprising aninfusion port in the area at the first circumferential location of theexpandable base for infusion of saline.
 6. The filter of claim 1,wherein the aspiration tube further comprises a turbine.
 7. The filterof claim 3, wherein the reservoir tip comprises latex.
 8. The filter ofclaim 7, wherein the latex covers a sector bounded by first and secondradii and the included arc of a circle.
 9. The filter of claim 1,wherein the filter is mounted on a cannula.
 10. The filter of claim 1,wherein the filter is mounted on an insertion handle.
 11. The filter ofclaim 10, wherein the aspiration tube extends proximally within theinsertion handle.
 12. The filter of claim 1, wherein the aspiration tubeextends proximally within an obturator.
 13. The filter of claim 9,wherein the aspiration tube extends proximally within the cannula.
 14. Amethod for protecting a patient from embolization, comprising the stepsof: inserting a filter into the patient's aorta, the filter comprising aporous material arranged in a generally conical shape having anexpandable base and a vertex, an elongate member having a proximal endand a distal end attached to the expandable base of the porous materialat a first circumferential location of the expandable base and extendingperpendicularly from a central axis of the filter, and an aspirationtube having a proximal end, a distal end, and a lumen therebetween, thelumen communicating with a port at the distal end, the distal end of theaspiration tube communicating with an area at the first circumferentiallocation of the expandable base; expanding the filter; aspirating embolithrough the suction port, wherein embolic material is removed from theaorta; and collapsing the filter and removing the filter form the aorta.15. The method of claim 14, further comprising the step of manipulatingthe aorta upstream of the filter.
 16. The method of claim 14, furthercomprising the step of inserting an aortic cannula for perfusion ofoxygenated blood.
 17. The method of claim 16, further comprising thestep of performing cardiopulmonary bypass.
 18. The method of claim 14,further comprising the step of performing cardiac surgery.
 19. Themethod of claim 14, wherein the filter further comprises a reservoirtip, and wherein the reservoir tip collects filtered embolic material.20. The method of claim 14, wherein the aspiration tube extendsproximally within an obturator.